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fifo_group.go
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/
fifo_group.go
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// Copyright 2015 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package fifo provides Group, which is a list of modifiers that are executed
// consecutively. By default, when an error is returned by a modifier, the
// execution of the modifiers is halted, and the error is returned. Optionally,
// when errror aggregation is enabled (by calling SetAggretateErrors(true)), modifier
// execution is not halted, and errors are aggretated and returned after all
// modifiers have been executed.
package fifo
import (
"encoding/json"
"net/http"
"sync"
"github.com/google/martian/v3"
"github.com/google/martian/v3/log"
"github.com/google/martian/v3/parse"
"github.com/google/martian/v3/verify"
)
// Group is a martian.RequestResponseModifier that maintains lists of
// request and response modifiers executed on a first-in, first-out basis.
type Group struct {
reqmu sync.RWMutex
reqmods []martian.RequestModifier
resmu sync.RWMutex
resmods []martian.ResponseModifier
aggregateErrors bool
}
type groupJSON struct {
Modifiers []json.RawMessage `json:"modifiers"`
Scope []parse.ModifierType `json:"scope"`
AggregateErrors bool `json:"aggregateErrors"`
}
func init() {
parse.Register("fifo.Group", groupFromJSON)
}
// NewGroup returns a modifier group.
func NewGroup() *Group {
return &Group{}
}
// SetAggregateErrors sets the error behavior for the Group. When true, the Group will
// continue to execute consecutive modifiers when a modifier in the group encounters an
// error. The Group will then return all errors returned by each modifier after all
// modifiers have been executed. When false, if an error is returned by a modifier, the
// error is returned by ModifyRequest/Response and no further modifiers are run.
// By default, error aggregation is disabled.
func (g *Group) SetAggregateErrors(aggerr bool) {
g.aggregateErrors = aggerr
}
// AddRequestModifier adds a RequestModifier to the group's list of request modifiers.
func (g *Group) AddRequestModifier(reqmod martian.RequestModifier) {
g.reqmu.Lock()
defer g.reqmu.Unlock()
g.reqmods = append(g.reqmods, reqmod)
}
// AddResponseModifier adds a ResponseModifier to the group's list of response modifiers.
func (g *Group) AddResponseModifier(resmod martian.ResponseModifier) {
g.resmu.Lock()
defer g.resmu.Unlock()
g.resmods = append(g.resmods, resmod)
}
// ModifyRequest modifies the request. By default, aggregateErrors is false; if an error is
// returned by a RequestModifier the error is returned and no further modifiers are run. When
// aggregateErrors is set to true, the errors returned by each modifier in the group are
// aggregated.
func (g *Group) ModifyRequest(req *http.Request) error {
log.Debugf("fifo.ModifyRequest: %s", req.URL)
g.reqmu.RLock()
defer g.reqmu.RUnlock()
merr := martian.NewMultiError()
for _, reqmod := range g.reqmods {
if err := reqmod.ModifyRequest(req); err != nil {
if g.aggregateErrors {
merr.Add(err)
continue
}
return err
}
}
if merr.Empty() {
return nil
}
return merr
}
// ModifyResponse modifies the request. By default, aggregateErrors is false; if an error is
// returned by a RequestModifier the error is returned and no further modifiers are run. When
// aggregateErrors is set to true, the errors returned by each modifier in the group are
// aggregated.
func (g *Group) ModifyResponse(res *http.Response) error {
requ := ""
if res.Request != nil {
requ = res.Request.URL.String()
log.Debugf("fifo.ModifyResponse: %s", requ)
}
g.resmu.RLock()
defer g.resmu.RUnlock()
merr := martian.NewMultiError()
for _, resmod := range g.resmods {
if err := resmod.ModifyResponse(res); err != nil {
if g.aggregateErrors {
merr.Add(err)
continue
}
return err
}
}
if merr.Empty() {
return nil
}
return merr
}
// VerifyRequests returns a MultiError containing all the
// verification errors returned by request verifiers.
func (g *Group) VerifyRequests() error {
log.Debugf("fifo.VerifyRequests()")
g.reqmu.Lock()
defer g.reqmu.Unlock()
merr := martian.NewMultiError()
for _, reqmod := range g.reqmods {
reqv, ok := reqmod.(verify.RequestVerifier)
if !ok {
continue
}
if err := reqv.VerifyRequests(); err != nil {
merr.Add(err)
}
}
if merr.Empty() {
return nil
}
return merr
}
// VerifyResponses returns a MultiError containing all the
// verification errors returned by response verifiers.
func (g *Group) VerifyResponses() error {
log.Debugf("fifo.VerifyResponses()")
g.resmu.Lock()
defer g.resmu.Unlock()
merr := martian.NewMultiError()
for _, resmod := range g.resmods {
resv, ok := resmod.(verify.ResponseVerifier)
if !ok {
continue
}
if err := resv.VerifyResponses(); err != nil {
merr.Add(err)
}
}
if merr.Empty() {
return nil
}
return merr
}
// ResetRequestVerifications resets the state of the contained request verifiers.
func (g *Group) ResetRequestVerifications() {
log.Debugf("fifo.ResetRequestVerifications()")
g.reqmu.Lock()
defer g.reqmu.Unlock()
for _, reqmod := range g.reqmods {
if reqv, ok := reqmod.(verify.RequestVerifier); ok {
reqv.ResetRequestVerifications()
}
}
}
// ResetResponseVerifications resets the state of the contained request verifiers.
func (g *Group) ResetResponseVerifications() {
log.Debugf("fifo.ResetResponseVerifications()")
g.resmu.Lock()
defer g.resmu.Unlock()
for _, resmod := range g.resmods {
if resv, ok := resmod.(verify.ResponseVerifier); ok {
resv.ResetResponseVerifications()
}
}
}
// groupFromJSON builds a fifo.Group from JSON.
//
// Example JSON:
// {
// "fifo.Group" : {
// "scope": ["request", "result"],
// "modifiers": [
// { ... },
// { ... },
// ]
// }
// }
func groupFromJSON(b []byte) (*parse.Result, error) {
msg := &groupJSON{}
if err := json.Unmarshal(b, msg); err != nil {
return nil, err
}
g := NewGroup()
if msg.AggregateErrors {
g.SetAggregateErrors(true)
}
for _, m := range msg.Modifiers {
r, err := parse.FromJSON(m)
if err != nil {
return nil, err
}
reqmod := r.RequestModifier()
if reqmod != nil {
g.AddRequestModifier(reqmod)
}
resmod := r.ResponseModifier()
if resmod != nil {
g.AddResponseModifier(resmod)
}
}
return parse.NewResult(g, msg.Scope)
}